Surface orientation dependent band alignment for CuInSe2–ZnSe–ZnO

Abstract

The interface formation and band-lineup between ZnO and epitaxial CuInSe2 substrates is investigated with photoelectron spectroscopy. ZnO films prepared by a metal-organic molecular beam epitaxy process lead to the formation of an intrinsic ZnSe buffer layer. The effect of substrate orientation on the band alignment is studied for the orientations (112) and (001). We found a weak dependence of the interfacial dipole on orientation. Together with our findings for CuInS2 films, we suggest a ubiquitous CuInX2–ZnX–ZnO (X=Se, S) structure with an ultra-thin ZnX buffer layer for ZnO growth on chalcopyrites at elevated temperatures.